Hydrodynamic transmission



April 27, 1943. w. D. TIPToN HYDRODYNAMIC TRANSMISSION Filed De. 2o,1941 2 sheets-sheet 1 vnu D April 27, 1943.

w. D. TIPToN HYDRODYNAMIC TRANSMISSION Filed Dec. 20, 1941 2Sheets-Sheet 2 www mmv

QW LT l INVENTOR 75 BWM ATTOR N EY5. 4

Patented Apr.` 27, 1943 UNITED STATES PATENT OFFICE 2,317,498 vHYDRODYNAMIC TRANSMISSION William D. Tipton, Baltimore, Md.

Application December 20, 1941, Serial No. 423,789

(Cl. 'i4-189.5)

38 Claims.

This application is a continuation-impart of my copending application,Serial No. 359,014, led September 30, 1940.

This invention pertains to power transmissions of the hydrodynamic typeand it relates in particular to improvements in hydrodynamictransmissions adapted for use in automotive vehicles.

It is the principal object of the present invention to provide animproved form of hydrodynamic transmission which shall have higheroperating efficiency and better acceleration characteristics than thoseof the prior art.

An additional object is to provide a transmission of the aforesaid typewhich includes two stages of torque conversion in addition to directdrive in its operating range.

A further object of the invention is to provide in such a transmission,novel control mechanism operable to provide the torque conversion ratiobest suited to the vehicle operating conditions at any particular time,this control mechanism being operable automatically in response totorque demand on the output shaft.

A still further object is to provide a fluid type transmission whereinrelatively great torque multiplication is obtained with small curvaturevanes thereby making possible the use of pressed metal varieswithresulting economy of manufacture as well as increased operatingeiiiciency.

A still further object is to provide in a transmission of the aforesaidtype, a pair of impeller or pump wheels geared together in such mannerthat one of the wheels is adapted to act as an auxiliary guide orreaction wheel under certain conditions of vehicle operation.

Additional objects and advantages of the invention will. become apparentfrom the following description which refers to the accompanyingdrawings, similar reference characters in said drawings designatingcorresponding parts in the description. y

In the drawings, Fig. 1 is a longitudinal elevational view, partly insection, of my improved transmission.

Fig. 2 is a diagram of the hydraulic circuit during the first stage oftorque conversion.

Fig. 3 is a similar diagram showing conditions during the second stageof torque conversion.

Fig. 4 is a diagram of conditions during direct drive.

Fig. 5 is a section along line 5-5 of Fig. l.

Fig. 6 is a section along line 6 6 of Fig. 1.

I Fig. 7 is a longitudinal sectional view of a modified form of theinvention.

- Fig. 8 is a section along line 8-8of Fig. 7.

The input structure of the transmission (referring to Figs. 1 to 6,inclusive) includes a ilywheel Illwhich is adapted to be driven by theengine crankshaft (not shown). The ywheel I 0 carries the usual startergear II and is fastened by bolts I2 to a housing member I3 whichpartially encloses the hydraulic unit. Housing I3 terminates in acylindricall portion I4 which cooperates with a suitable seal I5 toprevent escape of iluid from the hydraulic unit. The portion I4 isconnected by means of a dog clutch I6, to an annular member I1 which,.inturn, isbolted at I8 to a planet carrier I9.

The planet carrier I9 rotatably carries a pinion 20 which forms part ofa compound planetary gearset. The pinion 20 has two sets of teeth, theforward set 2l meshing with an annulus gear 22 and a sun gear 23, andthe rear set 24 meshing with an annulus gear 25.

The annulus gear 22 is formed integrally with a sleeve 26 which issplined at 21 to a hub 28 to which is riveted by rivets 29 a vanedimpeller or pump wheel 30. The sun gear 23 is connected by dog clutch 3|to the sleeve-like extension 32 of a second vaned impeller 33, thelatter being positioned in series relation relative to the main impeller39.

Also positioned in series relation with each other and with the wheels30 and 33 are a pair of vaned hydraulic elements designated 34 and 35respectively. The wheel 34 is adapted to function as a runner or turbinewheel and is splined at 3B to a shaft 31. The latter extends throughoutthe length of the transmission and is provided with an enlarged annulartoothed portion 38 adjacent the rear end which forms the annulus gear 39of a second compound planetary gearset.

'I 'he second or rear gearset includes a pinion 40 which is rotatablycarried by a carrier 4I, the latter being bolted at 42 to the enlargedhollowedout forward extension 43 of the output or tail shaft; 44. Thelatter is adapted to be connected to the rear axle of the vehicle fordriving the same.

The pinion 40 is provided with two sets of teeth 45 and 50 ofrespectively diierent pitch diameters. 'I'he teeth 45, oi' largerdiameter, mesh with the teeth of annulus gear 39 and sun gear 46respectively. 'Ihe gear 46 is formed integrally on the rear end of asleeve 41 which connected by a dog clutch 48 to a sleeve-like hub member49 which carries the hydraulic element 35. The teeth 50, of smallerpitch diameter, mesh with an annulus gear 5I and a. sun gear 62.

The annulus gear 5I is integrally carried by aY brake drum 53 which isadapted to be rotatively restrained by a brake band 54 under the controlof brake applying mechanism 55. The sun gear 52 is rotatable on thesleeve 41 and has a forwardly extending sleeve portion 56 Von which isformed a plurality of cams (Fig. 6). A set of overrunning rollers 51 isdisposed between the portion 56 and the cylindrical surface of a brakedrum 58 which is adapted for engagement by the brake band'59 undercontrol of brake applying mechanism 6U. Whenthe band 59 is set, rollers51 prevent reverse rotation of sun gear 52 while.

permitting free forward rotation thereof.

The annulus gear 25 which meshes with the rear teeth of the pinion 2 0has an integral hub 6l formed with cam surfaces 6| which form oneelement vof an overrunning brake device similar to that Just described.The second element thereof comprises an annular brake element 62, boltedto the casing at B3 and provided with a cylindrical portion with whichthe rollers 65 are adapted to engage and thereby lock gear 2 5 againstreverse rotation.

The operation of the device is as followsi To start the vehicle-fromrest, brake band 59 is set whereupon torque is supplied to planetcarrier I9 vfrom flywheel i0. Due to the shape of the vanes of wheel3l)` (see Fig. 2) at thestart there will be greater drag on wheel 30than kon wheel 35 therefore, as carrier I9 ls'rotated, wheel 33 will berotated at a speed greater than engine speed and the reaction on wheel30 will tend to rotate it in reverse. This tendency will cause therollers 65 to lock up against the stationary member 62 and reverserotation of wheel 30 will be prevented. The Wheel 30 will thereforefunction as a reaction Wheel.

The fluid delivered to wheel 34 will rotate the latter forwardly andtorque will thus be transmitted to annulus gear 39 of the rear planetarygearset. Forward rotation of gear 39 will tend to rotate sun gears 46and 52 in reverse. Sun gear 52 will be prevented from reverse rotationby lock-up of rollers 51 against brake drum 58, thus carrier 4| will berotated forwardly and torque willbe imparted through tail shaft 44 tothevehicle drive wheels (not shown). At the same time, the difference inpitch diameter of sun gears 46 and 52 will cause sun gear 46 to berotated in'reverse thereby causing reverse rotation of yhydraulic wheel35. The wheel 35 thus functions as a second reaction wheel and a secondstagev of hydraulic torque conversion is provided which actssimultanecusly'with the first stage.

' Fig.v '2 illustrates diagrammatically the fluid flow' in thehydraulicunit under the above dev scribed. conditions. It may thus be seen that,the

vehicleis started with two stages of hydraulic torque multiplicationacting in series with one stageofmechanical torque conversion, thelatter being obtained in the rearv planetary gearing.

j Upon acceleration of the car accompanied by a decrease in torquedemand on shaft 31, a. corresponding' decrease in reaction drag on wheel30 will occur. As the reaction force on wheel 30 decreases. the latterwill speed up causing impeller 33 to slow down until the two arerotating at the same speed. There will, under these conditions, be atendency for the front planetary set l these figures, avthirdoverrunning clutch device sion is operating in the second stage ofhydraulic torque multiplication combined with the stage of mechanicaltorque multiplication. This will result in the vehicle being drivenforwardly at increased speed and has the Leffect of a shift to second orintermediate speed in conventional transmissions.

Continued acceleration of the vehicle accompanied by further decrease intorque demand on shaft 44 results in a falling oi of the reaction forceonthe vanes of guide wheel and a decrease in slip between runner 34 andimpellers 30 and 33.` When the torque-demand on shaft 44 has reached avalue approximately-equal. to the torque supplied by impellers ,30 and.33, the reaction on guide wheel 35 lwill have entirely disappeared andthe outflow from the vane passage of runner 34 will become forwardlydirected, applying forward torque to 'wheel' 35. The guide wheel 35 willthen be rotated forwardly and the rollers 51 will release sunv gear 52for forward rotation. This causes lequalization of forces in the rearplanetary set'whereupon the gearset rotates as aA unit in'locked-upcondition and a direct drive condition obtains throughout thetransmission. Thisfcondition of operation in the hydraulicunit isdiagrammatically illustrated in Fig. 4 and corresponds to third speed inconventional transmissions. l.

It will Vbe noted that under these conditions, the wheels 30 and 33function as'inpu't wheels or impellers and thewheels 34f and"35 functionas output wheels or runners.

Reverse drive is obtained by release of brake band 59 and setting ofbrake band 55. Annulus gear 5l will then be locked against rotation andapplication of forward-driving torque to annulus gear 39 will causeforward rotation of pinion 40,

but because of the difference in pitch diameter of the teeth and 50 Aofthe pinion 40, reverse rotation will be impartedto carrier 4l and tailshaft 44, the teeth rolling around annulus gear 5| which also acts as arack. The vehicle.

will be obtained in the manner described above.

Direct drive in reverse'can never be obtained, however, because brakeVband 'maintains annulus 5| in stationaryfconditions which causes guidewheel {351to rotate in: reverse at all timesduring reverse dri-ve. f

Referring now to Figs. 7 and 8,y it will be seen` that in the formV ofthe invention illustrated by is operatively disposed between the wheels30 and 33. In` thesej figures,- similar' parts have been given the 'samereferencelnumerals .used to identify them in the abovedescription ofFigs. 1 to 6,V

inclusive. y

This additional'. overv. 'u'n'ri ing` clutch includes the cams 10 which4arey' f-,oin'edon the sleeve member 32, and rollers l1I v'vhichareretained in spaced relationship by tha-'usual cage.

The disposition of thecamsand; rollers is such that the wheel 33 4can`freely;overrun the wheel 30 as in the firstfstage Aof torque'conversiondescribed above. The wheel 30,1however, cannot overrun the wheel 33,lbut' is clutched to it by the rollers 'Il in response to such tendencyto overrun.

This arrangement of parts does not alter the operation of thetransmission, but is advantageous in that it prevents hunting of thewheels 30 and 33 which sometimes occurs when the change from ilrst stageto second stage of torque conversion takes place.

'In practice, the forward planetary gearset is ratioed such that therewill be a slight tendency for the wheel l0 to overrun the wheel 33 undernormal conditionsof torque demand. Thus, there will be a positivelock-up between these wheels after acceleration of the vehicle to thesecond conversion stage and all hunting will be avoided.

It will thus be seen that I have provided a power transmission that isfully automatic in operation and which provides a range of speed ratiosequal to that provided in conventional sliding gear transmissions. Whilebut two specific embodiments of my invention have been illustrated anddescribed, it is desired to point out that the invention may assume manydiderent forms and it is not desired tovlimit the invention in itsbroader aspects except as set forth in the claims appended hereto.

I claim:

i. In a hydrodynamic transmission having input and output structures, aplanet carrier carried by said input structure; a planet pinion carriedby said carrier; sun and annulus gears respectively meshing with saidpinion; a pair of vaned hydraulic wheels disposed in juxtaposition l andconnected respectively to said sun and annulus gears for rotationtherewith; a vaned runner wheel connected to the output structure anddisposed in such relation with respect to one of the aforesaid hydraulicwheels'that it receives the discharge therefrom; a second annulus gearin mesh with said pinion; and means for restraining rotation of saidlatter gear in the direction of rotational tendency thereof caused byfluid drag on said hydraulic wheels.

2. In a hydrodynamic transmission having input and output structures, aplanet carrier carried by said input structure; a planet pinion carriedby said carrier; sun and annulus gears respectively meshing with saidpinion; a pair of vaned hydraulic wheels disposed in juxtaposition andconnected respectively to said sun and annulus gears for rotationtherewith; a vaned runner wheel connected to the output structure anddisposed in such relation with respect to one of the aforesaid hydraulicwheels that itv tion and connected respectively to said sun and annulusgears for rotation therewith; a vaned runner wheel connected to theoutput structure and disposed in such relation with respect to one ofthe aforesaid hydraulic wheels that it receives the discharge therefrom;a second anlill nulus gear in mesh with said pinion; andoverrunningcontrol means for locking said second' annulus gear against reverserotation, said means permitting free forward rotation of said gear inresponse to a decreasel in slip between said runner and said wheels.

4. In a hydrodynamic transmission having input and output structures, aplanet carrier carried by said input structure; a planet pinion carriedby said carrier; sun and annulus gears respectively meshing with saidpinion; a pair oi vaned hydraulic wheels disposed in juxtaposition andconnected respectively to said sun and annulus gears for rotationtherewith; a'vaned runner wheel connected to the output structure anddisposed in such relation with respect to one of the aforesaid hydraulicwheels that it receives the discharge therefrom; a second annulus gearin mesh with said pinion; a member xed against rotation; and overrunningbrake means associated with said member and second annulus gear andoperable to lcclg the latter against reverse rotation while permittingfree forward rotation thereof.

5. In a hydrodynamic transmission having input and output structures, aplanet carrier carried by said input structure; a planet pinion carriedby said carrier; sun and annulus gears respectively meshing with saidpinion; a pair of vaned hydraulic wheels connected respectively to saidsun and annulus gears for rotation therewith, said wheels having theirrespective `inlet and outlet portions disposed at diierent radialdistances from the rotational axis of said wheels; a vaned runner wheelconnected to the output structure and arranged to receive the dischargefrom one of the aforesaid Wheels, a second annulus gear in mesh withsaid pinion; and means for locking said second annulus gear againstrotation in the direction of rotational tendency thereof caused by thedistribution of fluid drag on said hydraulic wheels.

6. In a hydrodynamic .transmission having input and output structures, aplanet carrier carried by said input structure; a planet pinion carriedby said carrier; sun and annulus gears respectively `meshing' with saidpinion; a pair of vaned hydraulic wheels connected respectively to saidsun and annulus gears for rotation therewith, said wheels having theirrespective inlet and outlet portions disposed at diierent radialdistances from the rotational axis of said wheels; a vaned runner wheelconnected to the output structure and arranged to receive the dischargefrom one of the aforesaid wheels; a second annulus gear in mesh withsaid pinion; and means for locking said second annulus gear againstrotation in the direction ofy rotational tendency thereof caused by thedistribution of fluid drag on said hydraulic Wheels during the period ofslip of said runner relative to said wheels.

7. In a hydrodynamic transmission having input and output structures, aplanet carrier car-A ried by said input structure; a planet pinioncarried by said carrier; sun and annulus gears respectively meshing withsaid pinion; a rst hydraulic wheel drivingly connected with said sungear; a second hydraulic wheel drivingly cono1' said second annulus gearwhereby said gear will function as a reaction-taking element.

8. In a hydrodynamic transmission having input and output structures, aplanet carrier carried by said input structure; a planet pinion carriedby said carrier; sun and annulus gears respectively meshing with saidpinion; a nrst hydraulic wheel drivingly connected with said sun gear; asecond hydraulic wheel drivingly connected with said annulus gear andarranged to receive the discharge from said rst wheel; the dischargeportion of said second wheel being disposed at greater radial distancefrom the rotational axis than the discharge portion of said first wheel;a. runner wheel arranged to receive the discharge from said secondwheel; a second annulus gear in mesh with said pinion; means for lockingsaid second annulus gear against reverse rotation whereby said secondwheel is caused to remain stationary and said rst wheel is rotated atoverspeed during the slip period of said runner.'

9. In a hydrodynamic transmission having input and output structures, aplanet carrier carried by said input structure; a planet pinion carriedby said carrier; sunl and annulus gears respectively meshing with saidpinion; a first hydraulic wheel drivingly connected with said sun gear;a second hydraulic wheel drivingly connected with said annulus gear andarranged to receive the discharge from said first wheel; the dischargeportion of said second wheel being disposed at greater radial distancefrom the rotational axis than the discharge portion of said first wheel;a runner Wheel arranged to receive the discharge fromsaid second wheel;asecond annulus gear in mesh -with said pinion; means for locking saidsecond annulus gear against reverse rotation whereby said second Wheelis causedto remain stationary and said first wheel is rotated atoverspeed during the slip` period of said runner; said locking meansbeing releasable to permit forward rotation of said second annulus gearin response to tendency thereof 'caused by decrease in slip between.said runner .and said first wheel. y

410.A In a hydrodynamic transmission having input and outputstructure-1s, a planet carrier carried by said input structure; a'planetpinion carried by said carrierfsun-and; annulus gears respectivelymeshing withvsaid, pinion; arst hydraulic wheel drivinglyconnected 'withsaid sun gear; a second vhydraulic wheel drivingly connected with saidannulus gear-and arranged to receive the discharge from said -flrstwheel; the discharge portion of said secondfwheel being disposed atgreaterradial-,ldistancejfrom the rotational axis -than thedischargeportion of said rst wheel; a runner wheel arranged to receive thedischarge fromsaid second wheel; a second annulus gear in mesh withsaidpinion; means for locking said second annulus gear against reverserotation whereby said "secondwheelis caused to remain stationary andsaid first wheel is rotated at overspeed during the slip period of saidrunner; said locking means beingreleasable to permit forward rotationofsaid second annulus gear in response to tendency .thereof caused bydecrease in slip between said runner and said first wheel thereby toVpermit rotation of lall of said wheels at substantially Videnticalspeed. l

l1. In a power transmission, a driving structure; a driven structure; apair of hydraulic runner wheels drivingly4 connected to the drivendisposed in driving relation relative to said runner wheels; meansdrivingly connecting the driving structure with said hydraulic impellerwheels including means for distributing the torque of said drivingstructure between said hydraulic wheels inversely in accordance with thehydraulic drag imposed thereon; and means drivingly connecting therunner wheels with the driven structure including means for applying thetorque of said wheels to said structure while said wheels are rotatingat diierent speeds relatively to one another.

12. In a power transmission, a driving structure; a driven structure; apair of turbine wheels connected to the driven structure; a pair of pumpwheels arranged in driving relationship relative to said turbine wheels;means for connecting said pump wheels with the driving structureincluding means for distributing the drive of said structure betweensaid pump wheels in a ratio inversely proportioned to the hydraulic dragimposed thereon; and means connecting said turbine Wheels with thedriven structure arranged to permit said wheels to vary in speedrelatively to one another whereby one of said wheels may act as a guidewheel.

13. The combination set forth in claim 12 wherein the connectingzmeansbetween the pump wheels and driving structure comprises a planetarygearset having the planet carrier thereof connected to said drivingstructure, the driven sun gear thereof connected to one of said pumpwheels and the driven annulus gearl thereof connected to the other ofsaid pump wheels.

14. The combination set forth in claim 12 wherein the connecting meansbetween the pump wheels and driving structure comprises a planetarygearset having the planet carrier thereof connected to said drivingstructure, the driven sun gear thereof connectedto one of said pumpwheels and the driven annulus gear thereof connected to the other ofsaid pump wheels; and means operatively associated with said gearset forlocking one of said driven gearsA against re- A verse rotation therebyto provide a reaction point for said gearset. v

structure; ap air of'hydraulic impeller wheels 75 15. In a powertransmission, a driving structure; a driven structure; a turbine wheeloonnected to the driven structure; rst and second pump wheels arrangedin driving relationship with said turbine wheel. said pump wheels havingtheir outlet portions disposed at respectively different distancesradially from the axisof rotation thereof, a planet gear carrierdrivingly connected to the driving structure; planet pinions carried bysaid carrier; a sun gear in mesh with said pinions and connected to saidfirst pump wheel; an annulus gear in mesh with said pinions andconnected to said second pump wheel; means for preventing reverserotational tendency of said annulus gear caused by difference in 'iluiddrag on said pump wheels during the period of slip of said turbine wheelrelative to said pump wheels whereby said second pump wheel is adaptedto function as a reaction wheel 'during'acceleration of said turbinewheel.

16. The combination set forth vin claim 15 wherein the means forpreventing reverserotational tendencyof the annulus gear comprises asecond annulus gear disposed in mesh with said planet pinion and brakemeans for locking said second annulus gear against reverse rotationwhile permitting free forward rotation thereof, l

whereby the second pump wheel is permitted to rotate forwardly at thespeed of the first pump wheel in response to falling off of reaction onsaid second wheel.

17. In a hydraulic power transmission, a driving structure; a drivenstructure; a. turbine wheel connected to the driven structure; a pair ofpump wheels connected to the driving structure: a reaction wheel: thedisposition of said wheels being such that the hydraulic fluid passessuccessively through said pump wheels to said turbine wheel, thence tosaid reaction wheel; means interposed in the drive connection betweenthe pump wheels and driving structure for permitting relative rotationbetween said wheels during driving including means for preventingreverse rotation thereof whereby one of said wheels may act as areaction wheel during initial acceleration of the turbine wheel; saidmeans being operable to permit said wheel to rotate in unison with theother pump Wheel in response to decrease in the slip of the turbinewheel thereby to provide a step-up in ratio through said transmission.

18. The combination set forth in claim 17 wherein means is provided forreleasing the reaction wheel for forward rotation in response to shiftin the direction of the impinging fluid caused by cessation of slip ofthe turbine wheel, thereby to provide a step-up to direct drive.

19. In a hydraulic power transmission, a driving structure; a drivenstructure; a turbine wheel connected to the driven structure; rst andsecond pump wheels connected to the driving structure; a reaction wheel;the disposition of said wheels being such that the hydraulic fluidpasses in succession through the first pump wheel, the second pumpwheel, the turbine wheel, tnence through the reaction wheel to the firstpump wheel; a planetary gearset interposed in the drive connection tosaid pump wheels and operable to distribute the drive between saidWheels in inverse proportion to the hydraulic drag imposed on saidwheels by the rotational resist-ance of said turbine wheel; a fixedelement operatively associated with said gearset for resisting reverserotational tendency of said second pump wheel whereby the latter iscaused to function as a reaction wheel thereby to provide one stage oftorque multiplication; and means for preventing reverse rotationaltendency of said reaction wheel thereby to provide a second stage oftorque multiplication.

20. The combination set forth in claim 19 wherein the planetary gearsetis operable to permit the pump wheels to rotate in unison in respense todecrease in slip of the turbine wheel thereby to effect a step-up indriving ratio.

21. The combination set forth in claim 19 wherein the planetary gearsetis operable to permit the pump wheels to rotate in unison in response todecrease in slip of the turbine wheel thereby to effect a step-up indriving ratio; and means for permitting forward rotation of the reactionwheel in response to reversal of fluid iiow impinging thereon thereby toeffect a second step-up in driving ratio.

22. The combination set forth in claim 19 wherein a planetarygearset isinterposed in the drive connection between the turbine wheel and theoutput shaft, said gearset being operable to provide a stage ofmechanical torque multiplication during operation of both stages cihydraulic torque multiplication.

23. The combination set forth in claim 19 wherein a planetary gearset isinterposed .in the drive connection between the turbine wheel and theoutput shaft, said gearset being operable to provide a stage ofmechanical torque multiplication during operation of both stages ofhydraulic torque multiplication; and means operably associated with saidgearset for establishing reverse rotation of the output during forwardrotation of the input shaft.

24. The combination set forth in claim 19 wherein a planetary gearset isinterposed in the drive connection between the turbine wheel and theoutput shaft; said gearset including an annuius gear connected to theturbine wheel; a. planet gear carrier connected to the output shaft anda sun gear connected to the reaction wheel; a second sun gear meshingwith the planet gears of said gearset; means for locking said second sungear against reverse rotation thereby to provide a reaction point forsaid reaction wheel during the slip period; said locking means beingreleasable to permit lock-up of the planetary gearset in l to l ratio inresponse to forward rotation of the reaction wheel.

25. in a power transmission, a driving structure; a pair of hydraulicpump wheels; means including a planetary gearset for connecting saidpump wheels with the driving structure; a driven structure; a pair ofhydraulic runner Wheels; means including a planetary gearset forconnect;- ing said runner wheels with the driven structure; the saidplanetary gearsets being so constructed and arranged with respect tosaid wheels and structures that said wheels may vary in yspeed withrespect to one another and said structures in accordance with thehydraulic drag imposed thereon.

26. The combination set forth in claim 2d wherein overrunning brakes arerespectively operably associated with one of said pump wheels and one ofsaid runner wheels for restraining reverse rotational tendency thereof,said brakes being releasable for permitting substantially synchronousforward rotation of said wheels.

27. In a hydrodynamic transmission having input and output structures, aplanet carrier carried by said input structure; a planet pinion carriedby said carrier; sun and annulus gears respectively meshing with saidpinion; a pair of vaned hydraulic wheels disposed in juxtaposition andconnected respectively to said sun and annulus gears for rotationtherewith; a vaned runner wheel connected tothe output structure anddisposed in such relation with respect to one of the aforesaid hydraulicwheels that it receives the discharge therefrom; a second annulus gearin mesh with said pinion; means for restraining rotation of said lattergear in the direction of rotational tendency thereof caused by uid dragon said hydraulic wheels, and clutch means operatively associated withsaid pair of vaned wheels for clutching the same together.

28. In a hydrodynamic transmission having input and output structures, aplanet carrier carried by said input structure; a planet pinion carriedby said carrier; sun and annulus gears respectively meshing with saidpinion; a pair ot vaned hydraulic wheels disposed in juxtaposition andconnected respectively to said sun and annulus gears for rotationtherewith; a vaned runner wheel connected to the output structure anddisposed in such relation with respect to one of the aforesaid hydraulicwheels that it receives the discharge therefrom: a second annulus gearin mesh with said pinion; means for preventing rotation of said lattergear in the direction of rotational tendency thereof caused by uid dragon said hydraulic wheels including releasable means permittingrotation'of said gear in the opposite direction, and clutch meansoperatively associated with said pair of vaned wheels for clutching thesame together.

29. In a hydrodynamic transmission having input and output structures, aplanet carrier carried by said input structure; a planet pinion carriedby said carrier; sun and annulus gears respectively meshing with saidpinion; a pair of vaned hydraulic wheels connected respective- 1y tosaid sun and annulus gears for rotation therewith, said wheels havingtheir respective inlet and outlet portions disposed at different radialdistances from the rotational axis of said wheels; a vaned runner wheelconnected to the output structure and arranged to receive the dischargefrom one of the aforesaid wheels, a second annulus gear in mesh withsaid pinion;

means for locking said second annulus gear against rotation in thedirection of rotational tendency thereof caused by the distribution offluid drag on said hydraulic wheels, and means for automaticallyclutching said pair of Wheels together in response to tendency of theWheel of larger diameter to overrun the other wheel.

30. In Lai hydrodynamic transmission l:having input andiVoutputstructures, a; planet-i carrier carried by said input structure; aplanet pinion carried by said carrier; sun and annulus gearsrespectively meshing with saidpinion; a pair of vaned hydraulic wheelsconnectedrespcctively to said sun and annulus gears forrotation'therewith,y said wheels having their respective;iniet andoutlet portions disposed at different radiall distances from therotationalaidspf said'wheels; and an overrunning clutch operativelydisposed between said wheels for clutching them together underfcertain.conditions of torque demand.- 1i 'ff af hydrodynamic ltransmissionhaving 1 input and output structures, a planet carrier carried bysaidinputstructure:a planet-pinion carried =by'said fcarrier; -sun `andannulus gears respectively meshingwith 'said- -pini'onr asnrst hydraulicwheel drivingly connected with said sun-'- gear," 'at secondl ihydraulic lwheel f :drivingly to receive vthe discharge fromsaid firstthe inlet and'outlet-portions of said rst and second wheels beingdisposed respectively atl dif.`

. riedby said carrier; sun and. annulus gears respectively meshing withsaid pinion; a rst hydraulic wheel drivingly connected with said sungear; a-second hydraulic wheel drivingly connected with said annulusgear andarranged to receive the discharge from saidl iirst wheel; thedischarge portion of said second wheel being disposed at greater radialdistance from the rota-V tional axis than the discharge portion of saidfirst wheel; a runner Wheel arrangedl to receive the discharge from saidsecond Wheel; a second f connectedi'with said annulus gearfand .arrangedremain stationary and said first wheel is rotated at overspeed duringthe slip period of said runner, and an overrunning clutch operativelydisposed between said irst and second wheels operable to permit saidiirst wheel to overrun said second kwheel and to clutch said secondwheel to said flrst wheel upon tendency of the former to overrun thelatter.

33. In a power transmission, a driving structure; a driven structure; ahydraulic runner drivingly connected to thedriven structure; a pair ofhydraulic members disposed in driving relation relative to said runner;means drivingly connecting the driving structure with said hydraulicmembers including means for distribut ingv the torque of said drivingstructure between said hydraulic members inversely in accordance withthe hydraulic drag imposed thereon, and clutch means operativelyassociated with said members for clutching them together for synchronousrotation.

34. In a power transmission, a driving structure; a driven structure; aturbine wheel connected ltothe ldriven structure;l a-.'pair of pumpwheels arrangedrin driving .relationship lrelative to said turbineWheel; means for connecting said pump wheels with the driving structureincluding means forl distributing the drive of said structure'betw'een.saidlpump wheels in a ratio in- Iversely proportioned to the hydraulicdrag imposed thereon,..'and clutch'means operatively as- ...sociatedwith said wheels operable automatically inv response "to' 'cessation of-slip between said .wheels for clutching them together.

y 35. The combination set forth in claim V34 wherein the connectingmeans between the'pump wheels 'and driving structure Acomprises a plane-Atary 'gearset having the planet carrierthereof connected to'saiddriving structure,l the'driven sun" 'gear 'thereof connected to one ofsaidpu'mp -wheels 'andthe driveny annulus"'gear thereo'fconnectedtothe'other of said pump, wheels.

36. The combination set forth in claim 34 wherein the connecting meansbetween the pump wheels and driving structure,coir'ipri'ses= a'plan'-connected to said-drivingfstructure the ldriven ysun gear thereofconnected tof one of said-pump for restraining one of said driven gearsfrom reverse rotation thereby to provide a reaction point for saidgearset.

37. In a hydraulic power transmission which includes a pair of inputwheels and a pair of output wheels, said wheels beingdisposed in seriesrelation; diilerential means drivingly connecting said input wheels, anddiierential means drivingly connecting said output wheels.

38. In .a hydraulic power transmission, a driving structure; a drivenstructure; a pair of input wheels; diierentia'l( means for drivinglyconnecting said input wheels with each other and with said drivingstructure; a pair of output wheels; and differential means drivinglyconnecting said output wheels with each other and with said drivenstructure.

WILLIAM D. TIPTON.

